Electronic measurements and instrumentation miscellaneous

Electronic measurements and instrumentation miscellaneous

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Electronic Measurements And Instrumentation

Electronic measurements and instrumentation miscellaneous
  1. Three phase four wire energy meter is used to measure:








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    Three phase four wire energy meter is used to measure three phase unbalanced energy.

    Correct Option: D

    Three phase four wire energy meter is used to measure three phase unbalanced energy.

  1. In the Miller sweep circuit:








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    In the miller sweep circuit A step input is converted into a linear ramp by using an operational integrator.

    Correct Option: B

    In the miller sweep circuit A step input is converted into a linear ramp by using an operational integrator.

  1. A galvanometer is tested shown in figure, in the circuit where, E = 1·5V R1 = 1·0 ohm, R2 = 2500 ohm and R3 is variable. With R3 set at 450 ohm, the galvanometer deflection is 140 mm and with R3 set at 950 ohm, the galvanometer deflection is 70 mm. The resistance of the galvanometer is:










  1. View Hint View Answer Discuss in Forum

    Given, E = 1·5V
    R2 = 2500Ω
    R1 = 1Ω
    R3 = variable
    RΩ = ?
    From given figure

    I =
    1.5
    		 =
    1.5
    Req[(R3 + RG)//R1] + R2

    or
    I =
    1.5
    R2 + {(R3 + RG)R1}/R3 + RGR1

    or
    I =
    1.5(R1 + R3 + RG)
    (R3 + RG + R1) + R2(R3 + RG)R1

    Now, Galvanometer current is given by relation
    IG = I ×
    R1
    R3 + RG

    when R3 = 450Ω, IG = 140 mm and
    when R3 = 950Ω, IG = 70 mm
    Applying these conditions, and manipulating the given parameters.
    We get RG ≈ 49Ω.


    Correct Option: C

    Given, E = 1·5V
    R2 = 2500Ω
    R1 = 1Ω
    R3 = variable
    RΩ = ?
    From given figure

    I =
    1.5
    		 =
    1.5
    Req[(R3 + RG)//R1] + R2

    or
    I =
    1.5
    R2 + {(R3 + RG)R1}/R3 + RGR1

    or
    I =
    1.5(R1 + R3 + RG)
    (R3 + RG + R1) + R2(R3 + RG)R1

    Now, Galvanometer current is given by relation
    IG = I ×
    R1
    R3 + RG

    when R3 = 450Ω, IG = 140 mm and
    when R3 = 950Ω, IG = 70 mm
    Applying these conditions, and manipulating the given parameters.
    We get RG ≈ 49Ω.


  1. Consider the following statements regarding the causes of error in current transformers:
    1. Some exciting mmf is required by the primary winding to produce a flux.
    2. The flux density in the core is not a linear function of the magnetising force.
    3. There is some magnetic leakage in the secondary winding.
    4. There is significant power consumption in the metering current. Of these statements:








  1. View Hint View Answer Discuss in Forum

    Causes of error in current transformers
    ● Some exciting mmf is required by the primary winding to produce a flux.
    ● There is some magnetic leakage in the secondary winding which produces large error in current transformer.
    ● There is significant power consumption in the metering current.

    Correct Option: D

    Causes of error in current transformers
    ● Some exciting mmf is required by the primary winding to produce a flux.
    ● There is some magnetic leakage in the secondary winding which produces large error in current transformer.
    ● There is significant power consumption in the metering current.

  1. The shunt type ohmmeter is NOT suitable for high resistance measurements because:








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    The shunt type ohm meter is not suitable for high resistance measurements because scale is highly cramped for high resistance values.

    Correct Option: B

    The shunt type ohm meter is not suitable for high resistance measurements because scale is highly cramped for high resistance values.